Manhole shield



July 22;, 1964 F. v. MALOON 3,142,234

MANHOLE SHIELD Filed Dec. 21, 1959 F IG .--|9 6 tl9 o INVENTOR.

FRED M MALOO/V ATTORNEYS United States Patent 3,142,234 MANHOLE SHIELDFred V. Maloon, 3117 Withers Ave, Lafayette, Calif. Filed Dec. 21, 1959,Ser. No. 861,082 6 Claims. (Cl. 94-48) This invention relates to amanhole shield adapted to be supported on a manhole frame when themanhole cover is removed to prevent water, dirt, tools and othermaterial from falling into the open manhole.

Heretofore, when a manhole cover for a manhole that opens into anunderground passageway, or an underground service chamber for servicingor repairing electrical, gas or water conduits etc., is removed, it iscustomary to position a shield around the frame opening to prevent toolsand foreign material above the surface of the ground from falling intothe opening and onto the workmen below the opening. These are caulkedaround the opening to prevent water, snow etc. on the street or abovethe surface of the area around the opening from passing through thelatter. This is a time consuming operation that is quite expensive,particularly where those installing the shield are skilled workmen whomay also do the repair or servicing work Within the underground chamberor passageway.

One of the objects of the present invention is the provision of amanhole shield that is economical to make and that may be installed andremoved in a matter of sev* eral minutes, and which shield, wheninstalled, effectively seals off the manhole against any leakage ofwater, sleet, snow, etc. between the shield and the frame.

Other objects and advantages will appear in the drawings anddescription.

In the drawings, FIG. 1, is a fragmentary, vertical sec tional view ofslightly more than half of the shield secured in place on a manholeframe, said view being taken along line 1-1 of FIG. 2.

FIG. 2 is a reduced size top plan view of the shield on a frame.

FIG. 3 is an enlarged fragmentary sectional View through one side of theshield and the manhole frame and an extension on said frame.

FIG. 4 is a slightly modified form of clamp adapted to be used on ashield.

FIG. 5 is a top plan view of a rectangular manhole frame with a shieldthereon.

FIG. 6 is an enlarged sectional view taken along line 66 of FIG. 5.

In detail a conventional circular manhole frame is indicated at 1, inwhich the upper inner corner of the frame is rabbeted to form a recessproviding a radially inwardly directed surface 2 and an axially upwardlydirected surface 3. An axially downwardly facing surface 4 is below theportion having the upwardly directed surface 3. Normally, the manholecover is formed with a rabbet complementary to the aforesaid rabbet inthe frame, so that a radially projecting portion on the cover rests inthe rabbet in the frame with the uppermost sur face of the cover flushwith the uppermost surface 5 of the frame. Where the frame is in a pavedstreet, the upper surface of the street is normally substantially flushwith the upper surface of the cover and frame.

The manhole shield that is shown in the drawings comprises acylindrical, vertically disposed wall 6 the outside diameter of which isslightly smaller than the inside diameter of the frame and this wall hasa radially outwardly directed annular flange 7 rigid therewith that isadapted to extend over the upper surface 5 of the frame for supportingthe wall on said frame in an upright position.

The wall 6 has a downwardly extending lower portion 8 below flange 7that may terminate at its lower edge approximately flush with theshoulder or axially downwardly facing surface 4 of the frame.

This lower portion 8 may be tapered inwardly along its lower terminatingedge to facilitate guiding the portion 8 into the manhole in setting upthe shield.

From the foregoing it will be seen that a generally rectangular spacewill be left between the shield and the frame defined by the lowersurfaces of the flange 7, the upper surface 3, the radially inwardlyfacing surface 2, and the outer surface of the portion of wall 6 that isbelow flange 7. The radially inwardly facing surface 2 of the frame isusually slightly inclined laterally outwardly in an upward direction.

Around the lower portion 8 of the wall 1 that is opposed to surface 2 onthe frame, is an expansible, fluid inflatable tube 9, which tube iscarried by the portion 8 in yieldable frictional engagement therewith,or it may be vulcanized or otherwise connected to the portion 8, if desired.

When inflated by any suitable source of fluid under presure through aconventional valve stem 10 having a conventional check valve, such as inan automobile or bicycle inner tube or tire, the tube 9 will expandradially outwardly and axially to form a tight fit in the space formedby the rabbet in the frame. Tube 9 is preferably molded to generallyconform to the cross sectional contour of the space formed by therabbet, although it may be cylindrical.

When the valve 10 is opened to permit escape of the air or whateverfluid is in the tube, the latter will collapse and will move away fromthe surface 5. Thus, in its collapsed position the tube will offer noobstruction to entering the rabbet in the frame, and will not becomechafed. In this connection, it should be mentioned that the lowerportion 8 of the wall 6, fits the inside of the frame below the rabbetthereon with suflicient accuracy to center the portion 8 in a mannerthat will prevent the tube 9 from sliding against the surface 2 when theshield is installed and removed.

The valve stem 10 may extend radially of the portion 8 to the inside ofthe shield, but preferably it is outside wall 6 and extends upwardlythrough the flange 7 so as not to interfere with a person entering themanhole or leaving it, and also, in the position extending throughflange 7 the latter will protect it against possible injury.

Projecting inwardly inside wall 6 are several pairs of verticallyaligned and vertically spaced bearings 13. Supported for verticalreciprocable movement by each pair of bearings is a vertically elongatedrod 14 carrying a jaw or clamping member 15 at its lower end and a head12 at its upper end.

The jaw or clamping member 15 on each rod 14 may be of the conventionaltype that is adapted to be moved upwardly at any time by the hand of anoperator, but which will be releasably locked against return or downwardmovement by a spring urged toothed cam 16 that is adapted to engage therod. The cam has a releasing lever 17 projecting therefrom. Uponpressing said lever away from rod 14 jaw 15 will be released to slidedownwardly but the cam will automatically engage the rod again uponrelease of the lever.

This clamping jaw 15 is only one suitable example of a structure thatmay be used.

Each rod 14 is cylindrical and may be rotated in the bearings so thatthe jaw thereon may be swung to a position projecting radially outwardlyof the wall 6 below its lower end position. When not in use the jaw maybe swung inwardly, and the lower portion of wall 6 is formed with adownwardly opening recess 18 (FIG. 1) in which the rod-mounted portionof jaw 15 is adapted to move 3 when the jaw is swung to radiallyinwardly projecting position and the shield is stored or carried. Thusthe clamping means may vertically be positioned wholly within thelaterally projected confines of the structure of the shield. It isobvious, of course, that the recess 18 may partially receive jaw 15 whenthe latter is in operative position should the manhole frame dimensionsbe such that the jaw must move into the recess in order to be operative.

Preferably the rod 14 is formed with vertically spaced openings 19 eachadapted to removably receive a pin 20 therein.

In certain instances where streets are repaved, the manhole frame wouldbe positioned below the upper surface of the added layer of paving,unless some means were provided to bring the cover supporting portion tothe level of the pavement. The usual structure for doing this is theprovision of a ring 21 (FIG. 3) that fits in the rabbeted portion offrame 1, and this ring, in turn, is formed with a rabbet that isidentical to that in the frame. This ring is of a thickness that equalsthe added paving on the old street.

Ring 21 has an upper surface 23 that corresponds to surface 3 of frame1, and a radially inwardly facing surface 24 that corresponds to surface2 of said frame.

In operation, where no ring is used (FIG. 1) the initial step inpositioning the shield, after the manhole cover is removed, is to insertthe lower portion 8 of the wall 6 in the opening in the frame so thatthe flange 7 will support the wall upright on the frame. The flange 7will, of course, rest on the uppermost surface of the frame.

The pin 20 in each rod 14 will be in the middle one of the threeopenings 19 shown in FIG. 1, in which position the clamping jaw, when atthe lower end of each rod, will be adapted to be swung to a positionbelow the downwardly facing shoulder 4 of the frame, which shoulder isthe lower surface of the portion 22 of the frame.

The clamping jaws are then moved upwardly until they engage said surface4, and thereafter the tube 9 is inflated.

When tube 9 is inflated, it will positively seal the space between thewall and the frame and will also form a seal between the flange 7 andthe frame. The flange 7 will cover the tube and will protect it, andassures a uniform pressure against the frame and will shield it at allpoints around the latter.

In the event the ring 21 is used, as seen in FIG. 3, the tube 9 will bepositioned within the rabbet that corresponds to that of the frame, andthe flange 7 will be supported on the uppermost surface of the ringoutwardly of said rabbet.

The pin 20, in the above instance, will be positioned in the uppermostof openings 19 in each rod, which will allow rod 14 to be lowered asuflicient distance to bring the jaw thereon below the surface 4 of thering. Each of the jaws may then be moved upwardly to engage surface 4,and the tube is inflated.

When the shield is collapsed for transport or carrying,

the pin 20 on each rod may be inserted in the lower of the openings, inwhich position the rods will be held within the shield.

As seen in FIG. 1 the pins 20, in each position of the rods, engage theupper bearings 13 of each pair thereof to limit the downward movement ofthe rods, pins 20 may be cotter pins or any other suitable pins adaptedto be releasably held in the openings 20.

The modification shown in FIG. 4 is one in which the shield itself,including its lower end portion, is identical with the shield of FIGS.1-3, hence the cylindrical wall 6 and its lower portion 8 will bear thesame numbers. Bearings 13 are also the same as in FIG. 1.

Bearings 13 have rods 25 reciprocably supplied thereon which rods may besubstantially the same as rods 14 except that they do not requireopenings 19 and in the modified form each rod is provided with alaterally projecting jaw 26 rigid therewith.

A helical spring 27 reacts between the upper bearing 13 and the head 28at the upper end of the rod to yieldably hold each rod in collapsedposition within the shield, when the jaws 26 are turned so they projectinto the shield.

In actual practice, after the shield is positioned on a manhole frame 1,as described for the shield of FIG. 1, the jaws 26 are drawn downwardlyagainst the resistance of springs 27 and are swung outwardly topositions below the portions 21 of the frame 1, and are released. Thejaws will then guidably hold the shield in position.

To remove the shield it is merely necessary to swing the jaws inwardlyand they will automatically be drawn into collapsed positions.

Recently certain municipalities have adopted rectangular manholestructures. FIG 5 is a top plan view of a manhole frame 30 that isrectangular, with corner recesses to receive corresponding extensions ona rectangular cover.

In this form of manhole frame the four sides are straight but eachcorner recess is formed with a ledge 31 thereon spaced a substantialdistance below the upper side of the frame that is adapted to have itsunderside engaged by a clamping jaw similar to that shown in FIG. 3 or4.

In this form of invention, the shield itself will have flat rectangularwalls 32 having a flange 33 (FIG. 6) adapted to overlie the uppermostsurface of the frame. The lower portion of the shield will be anintegral extension of walls 32 projecting into the rectangular spaceenclosed by the latter providing a laterally outwardly opening channel34 in which an expansible tube 35 is positioned. This tube will be inopposed relation to the inner surfaces of the sides of the shield alongthe uppermost edge of the frame. When it is inflated it will form atight seal between the frame and the shield.

Rods 36 are mounted for vertical reciprocation in bearings 37 mounted onthe vertically designed bottom of channel 34. Springs 38 are interposedbetween the heads 39 of the rods and the bearings to yieldably urge therods upwardly. Jaws 40 respectively on the lower ends of rods 36 areadapted to engage the under sides of the ledges 31 in each cornerrecess. The tube 35 will accommodate itself to any irregularities incontour at the corners of the frame.

From the foregoing description, it will be apparent that only a fewminutes time will be required to install a shield or to remove it.

It is not intended that the detailed description shall constitutelimitations on the invention. The claims appended hereto are intended tocover such modifications as may be made within the scope of theinvention.

I claim:

1. A shield for use on a horizontally disposed, centrally open manholeframe that defines the outline of a manhole comprising: an open endedvertically disposed rigid tube having an upper portion and a lowerportion and a horizontally disposed flange rigid with said tube adaptedto extend over and directly engage the upper surface of such frame forsupporting said upper portion directly on said frame coaxial with thelatter and projecting upwardly thereon and for supporting said lowerportion within such frame, an air inflatable tube below said flange andaround said lower portion expansible upon inflation with air from acollapsed position out of sealing engagement with said frame when saidflange is on and in engagement with the latter whereby said rigid tubemay be removed from said frame without injury to said inflatable tube,to an expanded position in sealing engagement with said flange, lowerportion and such frame, and means on said rigid tube adapted topositively but releasably lock said rigid tube rigid with such frame andto hold said flange against the upper side of said frame when saidinflatable tube is inflated.

2. A shield for use on a horizontally disposed, centrally open manholeframe that defines the outline of a manhole comprising: an open endedvertically disposed rigid tube having an upper portion and a lowerportion and a horizontally disposed flange rigid with said tube adaptedto extend over and directly engage the upper surface of such frame forsupporting said upper portion directly on said frame coaxial with thelatter and projecting upwardly thereon and for supporting said lowerportion within such frame, an air inflatable tube below said flange andaround said lower portions expansible upon inflation with air from acollapsed position out of sealing engagement with said frame when saidflange is on and in engagement with the latter whereby said rigid tubemay be removed from said frame without injury to said inflatable tube,to an expanded position in sealing engagement with said flange, lowerportion and such frame, and means on said rigid tube adapted topositively but releasably lock said rigid tube rigid with such frame andto hold said flange against the upper side of said frame when saidinflatable tube is inflated, said flange terminating at its outerperipheral edge a distance from said lower portion to fully extend oversaid inflatable tube and the upper surface of said frame only wherebysaid flange will be adapted to seat against the upper surface only ofsaid frame to thereby be free from the influence of irregularities inpavement that may be around and extend to said frame.

3. In combination with a horizontally disposed manhole frame having ahorizontally disposed upper surface; a central manhole opening formed insaid frame having vertical sides defining the outline of said opening;said frame being rabbeted to provide a recess in said frame around saidopening at the upper end thereof having an axially upwardly facingsurface and an adjoining radially inwardly facing surface respectivelyadjoining said upper surface and said vertically extending sides; atubular open ended shield coaxial with said opening having a lowerportion extending into said opening downwardly past said recess and anupper portion projecting upwardly from said opening; a horizontallydisposed rigid flange rigid with said shield at the upper end of saidlower portion extending horizontally over said recess and in engagementwith said upper surface supporting said shield on said frame; aninflatable expandable tube of elastic, rubber-like material around theupper end of said lower portion and below said flange disposed in saidrecess, said tube being inflatable with air from a collapsed positionwithin said recess out of sealing relation with said radially inwardlyfacing surface of said recess to an expanded position in sealingrelation with said lower portion, said flange and said radially inwardlyand axially upwardly facing surfaces of said recess, means for inflatingand deflating said tube, and locking means carried by said shield inlocking engagement with said frame for holding said flange against saidupper surface when said inflatable means is inflated.

4. In combination with a horizontally disposed manhole frame having ahorizontally disposed upper surface; a central manhole opening formed insaid frame having vertical sides defining the outline of said opening;said frame being rabbeted to provide a recess in said frame around saidopening at the upper end thereof having an axially upwardly facingsurface and an adjoining radially inwardly facing surface respectivelyadjoining said upper surface and said vertically extending sides; atubular open ended shield coaxial with said opening having a lowerportion extending into said opening downwardly past said recess and anupper portion projecting upwardly from said opening; a horizontallydisposed rigid flange rigid with said shield at the upper end of saidlower portion extending horizontally over said recess and in engagementwith said upper surface supporting said shield on said frame; aninflatable expandable tube of elastic, rubberlike material around theupper end of said lower portion and below said flange disposed in saidrecess, said tube being inflatable with air from a collapsed positionwithin said recess out of sealing relation with said radially inwardlyfacing surface of said recess to an expanded position in sealingrelation with said lower portion, said flange and said radially inwardlyand axially upwardly facing surfaces of said recess, means for inflatingand deflating said tube, and locking means carried by said shield inlocking engagement with said frame for holding said flange against saidupper surface when said inflatable means is inflated, said frame beingimbedded in pavement extending to said upper surface of said frame andsaid flange terminating at its outer peripheral edges short of saidpavement as to be supported solely by said frame and independently ofsaid pavement whereby said flange will seat against said upper surfacefree from the influence of irregularities in contour of the pavementadjoining said frame.

5. In combination with a horizontally disposed annular manhole framehaving a central opening for passage of a man therethrough, said framebeing rabbeted circumferentially thereof along its upper and radiallyinwardly facing sides to provide an annular recess coaxial with theframe having adjoining axially upwardly and radially inwardly facingsurfaces; a tubular, cylindrical, vertically disposed shield in aposition coaxial with said frame removably extending at its lower endportion into said opening and past said recess and having an upperportion projecting a substantial distance above said frame, a radiallyoutwardly extending flange rigid with said shield extending over saidrecess and the uppermost surface of said frame adjoining the lattersupporting said shield on said frame in said position whereby saidflange, said axially upwardly facing and radially inwardly facingsurfaces of said recess and the radially outwardly facing surface ofsaid lower portion of said shield coact to provide the walls of anannular passageway around said shield below said flange; an annular, airinflatable tube of flexible, elastic material within said passagewayexpansible upon inflation thereof with air to tightly engage said wallsof said passageway for forming a seal between said shield and said frameto prevent water outside said shield and above the level of said framefrom entering said central opening in said frame, and quick releasablelocking means carried by said shield within the latter including spacedframe engaging members separately and releasably engaging said frame atspaced points around said frame and spaced below said recess for holdingsaid shield rigidly in said position with said flange over said recess.

6. In a construction as defined in claim 5, said quick releasablelocking means comprising rods extending vertically along the radiallyinwardly facing surfaces of said shield, means for supporting said rodson said shield for rotation about their vertical axis, said frameengaging members projecting laterally from the said rods and beingmovable from frame engaging positions projecting radially outwardlyrelative to the axis of said shield and across the lower edge of thelatter to a shield releasing position in which they project radiallyinwardly relative to said last mentioned axis and to positions withinthe downwardly projected confines of the outline of said shield toenable upward removal of said shield from said frame.

References Cited in the file of this patent UNITED STATES PATENTS1,908,909 Manz May 16, 1933 1,957,162 Erickson May 1, 1934 2,281,633Stitzer May 5, 1942 2,559,564 Sperling July 3, 1951 2,757,225 Dunn July31, 1956 3,007,600 Horner Nov. 7, 1961 FOREIGN PATENTS 547,072 GreatBritain Aug. 12, 1942

1. A SHIELD FOR USE ON A HORIZONTALLY DISPOSED, CENTRALLY OPEN MANHOLEFRAME THAT DEFINES THE OUTLINE OF A MANHOLE COMPRISING: AN OPEN ENDEDVERTICALLY DISPOSED RIGID TUBE HAVING AN UPPER PORTION AND A LOWERPORTION AND A HORIZONTALLY DISPOSED FLANGE RIGID WITH SAID TUBE SURFACEOF SUCH FRAME FOR SUPPORTING SAID UPPER PORTION DIRECTLY ON SAID FRAMECOAXIAL WITH THE LATTER AND PROJECTING UPWARDLY THEREON AND FORSUPPORTING SAID LOWER PORTION WITHIN SUCH FRAME, AN AIR INFLATABLE TUBEBELOW SAID FLANGE AND AROUND SAID LOWER PORTION EXPANSIBLE UPONINFLATION WITH AIR FROM A COLLAPSED POSITION OUT OF SEALING ENGAGEMENTWITH SAID FRAME WHEN SAID FLANGE IS ON AND IN ENGAGEMENT WITH THE LATTERWHEREBY SAID RIGID TUBE MAY BE REMOVED FROM SAID FRAME WITHOUT INJURY TO